The work represents an investigation of factors that may effect elastin synthesis in major vessels. Current work is focused on the role of a proelastin or tropoelastin-protein complex in the biosynthesis of elastin in aorta of chicks fed diets sufficient or deficient in dietary copper. Further, the effect of such factors as dietary cholesterol (to induce atherosclerosis), hyperinsulinemia, diabetes, hypertension on alterations in elastin biosynthesis are currently under investigation. Work to date suggests that in copper-deficiency, soluble elastin in aorta extracts first appears as a short-lived complex or proelastin that is modified to tropoelastin before incorporation into fibrous elastin. Data also suggest that once elastin is formed into a crosslinked fiber, it is extremely resistant to modification in vivo; even in severely atherosclerotic vessels.